1. Field of the Invention
The present invention discloses a method for detecting and eliminating the flash scene in digital video with respect to the video content analysis and TV program management. One of the important issues is to obtain the accurate shot information and discover the flash scene herein.
2. Description of Related Art
Flash scenes usually appear in many kinds of digital video such as fashion shows, concert, sport TV broadcasting, etc. Usually, the camera's flash lamp or other optical instruments cause those scenes due to the photographer tries to enhance the quality of the pictures. Moreover, special editing, such as after-treatment, usually employs flash scenes to catch consumers' attention. Flash scenes, however, bring the captured video not only the quality related to the receptiveness of the audiences, but also the accuracy of content analysis such as shot detection. It is thus desirable to develop an algorithm that detects and removes these disturbing abrupt scenes for human eyes.
Flash scenes also cause lots of unwanted shots that are supposed to belong to the same shots. Generally, accuracy of shot detection is essential and usually the primary step to do the video content analysis. Therefore, the development of this algorithm is urgent and important.
FIG. 1 shows a flow chart of an operation method for scene/shot change detector described in USPTO Pub. No. 2004/0008284A1. Wherein the detector includes frame buffer storing two image frame data, which are converted into color signals. Then the detector detects the scene/shot change by calculating the histograms from those color signals of video. The method thereof comprises:
Two image frame data are stored in the frame buffers individually for detecting scene/shot change (step S150); and the image frame data stored in buffers are converted into chroma or brightness color signal (step S152); a histogram detection unit calculates the histograms respect to converted chroma luminance color signal (step S154); then a dependence value (in USPTO Pub. No. 2004/0008284A1, this value is termed a correlation value) C is calculated with respect to the two histograms (step S156); and comparing the value C with a preset threshold, and determining whether the value C is smaller than the threshold (step S158); if the value C is smaller than the threshold, the scene/shot change signal Csc is outputted as 1 (Csc=1), or Csc equals to 0 (step S160, S162).
In conclusion, the art shown in FIG. 1 illustrated the method for detecting the scene/shot change which is calculated from the comparison between the signals converted from two stored image frames in histogram and a preset threshold.
Further reference is made to FIG. 2 showing the USPTO Pub. No. 2003/0123726A1, which is a block diagram illustrating an apparatus for detecting a scene/shot change. The apparatus comprises a first accumulated histogram extracting part 201, a first pixel list extracting part 202, a second accumulated histogram extracting part 203, a second pixel list extracting part 204, a histogram comparing part 205 and a scene change determining part 206. The accumulated histograms of a first frame I1 and a second frame I2 being adjacent to the first frame I1 are extracted to the first accumulated histogram extracting part 201 and second accumulated histogram extracting part 203 respectively.
After that, the first pixel list extracting part 202 extracts a pixel list C1 corresponding to an accumulated distribution value from the first accumulated histogram extracting part 201. Simultaneously the second pixel list extracting part 204 extracts a pixel list C2 from the second accumulated histogram extracting part 203. Then, the histogram comparing part 205 compares the outputs L1, L2 of the first and second pixel list extracting parts 202, 204. Finally, the scene conversion determining part 206 analyzes the output of the frame difference E with a predefined threshold from the histogram comparing part 205, and determines whether the scene/shot change occurs thereby.
By repeating the steps for detecting the scene/shot change aforementioned, a memory is required for storing the differences, then, the averaging difference among the frames nearby is calculated to determine the scene/shot change.
The methods in the prior arts have been proposed to deal with detection of flash scenes. Most of them are incorporated to analyze an individual frame for finding out high intensity of pixel luminance value. However, the misdetection always occurs since the frame exists on large-scale white background. Nevertheless, it is still difficult to determine whether the image involves a flash scene only by a threshold value that reflects the percentage of high intensity region therein.
In view of the drawback of the prior art, efficient detection and elimination of flash scenes is one of the important issues for obtaining accurate shot information. Shot detection is usually the first step for any visual content analysis such as indexing, skimming and abstraction. The present invention discloses the video content analysis and processing for video management.